Studies on Curing Kinetics Parameter of TDI-PPG-MOCA Polyurethane by FTIR

2011 ◽  
Vol 328-330 ◽  
pp. 966-969 ◽  
Author(s):  
Qing Zhen Wen ◽  
Chao Yu ◽  
Jin Hua Zhu ◽  
Tian Yu Liu
Keyword(s):  
Reaction Rate ◽  
Curing Kinetics ◽  
Crosslinking Reaction ◽  
Curing Process ◽  
Second Order Reaction ◽  
Reaction Rate Constants ◽  
Curing Reaction ◽  
Different Temperatures ◽  
Measured Effect ◽  
Kinetics Parameter

The curing process of polyurethanes was investigated with FTIR method. The curves of conversion (α)VS curing reaction time (t) at different temperatures were obtained .The curing reaction of the system was found to be second order reaction. The reaction rate constants and activation energy had been measured. Effect of the use lever of curing agent and temperatures on curing reaction was discussed. The results showed that when the mole ratio of NCO/OH is smaller than 1, the crosslinking reaction take place at high temperature.

scholarly journals Construction of a TTT-η Diagram of High-Refractive Polyurethane Based on Curing Kinetics

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3474
Author(s):  
Shidi Huang ◽  
Guiming Zhang ◽  
Weiping Du ◽  
Huifang Chen
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Gelation Time ◽  
Curing Kinetics ◽  
Processing Parameters ◽  
Curing Process ◽  
Scanning Calorimetry ◽  
Different Temperatures ◽  
Temperature Transformation

A time–temperature–transformation–viscosity (TTT-η) diagram can reflect changes in the physical states of a resin, which take on significance for the study of the curing process of polyurethane resin lenses. Coupling the differential scanning calorimetry (DSC) test, the curing kinetic parameters of 1,4-bis(isocyanatomethyl)cyclohexane (H6XDI)/2,3-bis((2-mercaptoethyl)thio)-1-propanethiol (BES) polyurethane system were obtained. By phenomenological modeling, the relationships between degree, temperature, and time were obtained. An isothermal DSC test was carried out at 423 K. Based on the DiBenedetto equation, the relationships between glass transition temperature, degree of cure, and time were obtained, and the glass transition temperature was thus correlated with temperature and time. The gelation time at different temperatures was measured by rotary rheometry, and the relationship between gelation time and gelation temperature was established. The time–temperature–transformation (TTT) diagram of H6XDI/BES system was constructed accordingly. Subsequently, a six-parameter double Arrhenius equation was used as the basis for the rheological study. The viscosity was examined during the curing process. The TTT-η diagram was obtained, which laid the theoretical foundation for the optimization and setting of processing parameters.

Development of a model for predicting reaction rate constants of organic chemicals with ozone at different temperatures

Chemosphere ◽  
2013 ◽  
Vol 92 (8) ◽  
pp. 1029-1034 ◽  
Author(s):  
Xuehua Li ◽  
Wenxing Zhao ◽  
Jing Li ◽  
Jingqiu Jiang ◽  
Jianji Chen ◽  
...  
Keyword(s):  
Rate Constants ◽  
Reaction Rate ◽  
Organic Chemicals ◽  
Reaction Rate Constants ◽  
Different Temperatures

scholarly journals Positronium in a Liquid Phase: Formation, Bubble State and Chemical Reactions

2012 ◽  
Vol 2012 ◽  
pp. 1-17 ◽  
Author(s):  
Sergey V. Stepanov ◽  
Vsevolod M. Byakov ◽  
Dmitrii S. Zvezhinskiy ◽  
Gilles Duplâtre ◽  
Roman R. Nurmukhametov ◽  
...  
Keyword(s):  
Energy Deposition ◽  
Reaction Rate ◽  
Local Heating ◽  
Bubble Radius ◽  
Annihilation Rate ◽  
Electron Pairs ◽  
Reaction Rate Constants ◽  
Slowing Down ◽  
Diffusion Controlled ◽  
Different Temperatures

The present approach describes the e+ fate since its injection into a liquid until its annihilation. Several stages of the e+ evolution are discussed: (1) energy deposition and track structure of fast positrons: ionization slowing down, number of ion-electron pairs, typical sizes, thermalization, electrostatic interaction between e+ and the constituents of its blob, and effect of local heating; (2) positronium formation in condensed media: the Ore model, quasifree Ps state, intratrack mechanism of Ps formation; (3) fast intratrack diffusion-controlled reactions: Ps oxidation and ortho-paraconversion by radiolytic products, reaction rate constants, and interpretation of the PAL spectra in water at different temperatures; (4) Ps bubble models. Inner structure of positronium (wave function, energy contributions, relationship between the pick-off annihilation rate and the bubble radius).

scholarly journals Stability of vitamin C in broccoli at different storage conditions

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Nasser Al-Habsi ◽  
Sithara Suresh ◽  
Amani Al-Yhmedi ◽  
Marwa Al-Shoryani ◽  
Mostafa I. Waly ◽  
...  
Keyword(s):  
Activation Energy ◽  
Vitamin C ◽  
Reaction Rate ◽  
Storage Conditions ◽  
Order Reaction ◽  
Titration Method ◽  
First Order ◽  
Reaction Rate Constants ◽  
Different Temperatures ◽  
Thermal Stability Of

In this study, the retention of vitamin C in fresh broccoli stored at different temperatures (i.e. chiller, room, cooking, and roasting or baking; 5-120°C) was investigated. The thermal stability of vitamin C in broccoli was analysed at 5, 20, 45, 60, 70, 80, 110, and 120°C. The vitamin C content was measured by the indophenol titration method. Vitamin C was affected negatively at all stored temperatures. The degradation of vitamin C was modelled by first-order reaction kinetics and the reaction rate constants were observed as 9.03×10-8 and 5.65×10-3 s-1 when stored at 5°C and 120°C, respectively. The activation energy was estimated as 74.2 kJ/mol within the temperature range used in this study. The lowest decay of vitamin C was observed during the chilling condition. The data on retention of vitamin C in broccoli could be used to determine their stability, when stored as raw, and when heated at different temperatures.

scholarly journals The transition nanoreactor-nanoparticle in epoxy polymers curing process

2008 ◽  
Vol 2 (4) ◽  
pp. 281-284
Author(s):  
Georgiy Kozlov ◽  
◽  
Musa Bashorov ◽  
Abdulakh Mikitaev ◽  
Gennady Zaikov ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Euclidean Space ◽  
Reaction Rate ◽  
Typical Feature ◽  
Reaction Rate Constant ◽  
Conversion Degree ◽  
Curing Process ◽  
Epoxy Polymers ◽  
Curing Reaction ◽  
Fractal Space

It has been shown that for curing reaction in fractal space the reaction rate constant reduction is typical. Another typical feature of this reaction is the formation of a large number of microgels with smaller molecular weight in comparison with reaction in Euclidean space at the same conversion degree. The dimensional border between nanoreactor and nanoparticle for the curing reaction under consideration has been obtained.

scholarly journals Rheokinetic study of crosslinking of α,ω-dihydroxy oligo(alkylene maleate)s with a trisisocyanate

2003 ◽  
Vol 68 (3) ◽  
pp. 147-162 ◽  
Author(s):  
Branko Dunjic ◽  
Jasna Djonlagic ◽  
Slavko Vukasinovic ◽  
Maurice Sepulchre ◽  
Marie-Odile Sepulchre ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Reaction Rate ◽  
Loss Modulus ◽  
Phase Segregation ◽  
Mechanical Analysis ◽  
Rheological Parameters ◽  
Crosslinking Reaction ◽  
Curing Process ◽  
Segmental Mobility ◽  
Time Curve

The crosslinking reaction of three series of ?,?-dihydroxy oligo(alkylene maleate)s with a trifunctional isocyanate was followed by dynamic mechanical analysis and FTIR spectroscopy. The evaluation of rheological parameters such as storage G? and loss modulus G", was recorded. A typical G?versus time curve has a characteristic "S" shape, indicating autoacceleration of the crosslinking reaction. The whole curing process starting from G?equal G", or the beginning of gelation is described by a second - order phenomenological rheokinetic equation which takes into account the autoacceleration effect, the latter being a consequence of the superposition of both the chemical reaction and phase segregation. It appears that the crosslinking reaction rate depends on the concentration of the functional groups, i.e., on the molecular weight of the polyester prepolymer and on the length of the aliphatic sequence in the repeating unit or the segmental mobility. The crosslinking rate decreases in the order: poly(octamethylene maleate) > poly(hexamethylene maleate) > poly(butylene maleate).

Phenomenological effect of temperature on the order n of the reaction of the curing kinetics in an EPDM polymer

2021 ◽  
pp. 1-12
Author(s):  
Salvador Gomez-Jimenez ◽  
Ana Maria Becerra-Ferreiro ◽  
Eduardo D Jareño-Betancourt ◽  
Jose M Vazquez-Penagos
Keyword(s):  
Cure Kinetics ◽  
Analytical Description ◽  
Curing Kinetics ◽  
Effect Of Temperature ◽  
Crosslinking Reaction ◽  
Precise Control ◽  
The Best Approximation ◽  
Short Period ◽  
Different Temperatures ◽  
Kinetics Of

Abstract The precise control of curing reaction parameters allows a better crosslinking polymer. Modeling and optimization of this process require a correct kinetic of curing model. The kinetics of the crosslinking reaction is studied for the ethylene propylene diene monomer (EPDM) synthetic elastomer by movile die rheometer (MDR). The kinetic parameters of reaction were calculated from Kamal-Ryan, Sestak-Berggren, and the Isayev-Deng methods at different temperatures. An Arrhenius-type function for the order of reaction n is introduced to improve the adjusting. A comparative study of Sestak-Berggren and Isayev-Deng models was made to validate and determine which model best describes the behavior of vulcanization. The best approximation was obtained with the model Isayev-Deng. Finally, taking the model with the best fit, a graphical and analytical description of the cure kinetics was developed. The order of reaction is predicted to better establishment of processing time. It was noted that for EPDM at higher temperatures, the increase of the rate of reaction occurs in short period of time, which could cause premature curing if the supply system is inadequate.

Curing Kinetics of Anisotropic Conductive Adhesive in the Manufacturing Process of RFID Tags

2013 ◽  
Vol 798-799 ◽  
pp. 17-24
Author(s):  
Shou Yuan Fan ◽  
Jian Kui Chen ◽  
Zhou Ping Yin
Keyword(s):  
Activation Energy ◽  
Curing Kinetics ◽  
Conductive Adhesive ◽  
Curing Process ◽  
Heating Rates ◽  
Degree Of Cure ◽  
Anisotropic Conductive Adhesive ◽  
Curing Reaction ◽  
Model Free ◽  
Kinetics Of

The study of the epoxy-based anisotropic conductive adhesive in electronic packaging interconnects applications (chip-on-glass, chip-on-flex, etc. especially in RFID applications) has received particular attention. This is due to its potential advantages of finer pitch printing, reducing environmental contamination. The thermal curing process is critical to develop the ultimate electrical and mechanical properties of the ACA devices. In this article, the curing kinetics of ACA was studied with a differential scanning calorimeter (DSC) under constant heating rates conditions in the range of 520 °C/min. The model free method was used to describe the curing reaction. The degree-of-cure and the activation energy through the whole conversion range were mathematically determined and used to predict the progress of the curing process. Experimental results show that the activation energy of the ACA varies significantly with degree-of-cure during the curing process. The peculiar phenomenon indicates that the ACA underwent a complex series of reactions. The kinetics of curing reaction changes when large conversion values are reached at low heating rates. The change in the reaction kinetics is due to vitrification of the ACA during heating. In addition, the degree-of-cure of the ACA as a function of bonding times during isothermal ACA bonding process was theoretically predicted.

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